Dark Knight's Gotham City environments and most of the action sequences were assigned to Double Negative, which created more than half the of the 700 vfx shots. All images ™ & © ; DC Comics. Courtesy of Warner Bros.

The Dark Knight (now playing from Warner Bros.), not surprisingly, sets itself apart from the average vfx-based summer blockbuster. With around 700 vfx shots, director Christopher Nolan's purpose once again was not to wow viewers, but to serve a story in which Batman confronts two of his arch enemies, the Joker and Harvey Two-Face.

Working with Visual Effects Producer Joyce Cox and VFX Supervisor Nick Davis oversaw a global effort that involved vendors based in America, England and France. "Chris Nolan had had a very positive experience with the work that had been achieved on the first movie [Batman Begins], and he wanted to maintain the same gritty, super realistic approach to the visual effects," Davis explains. "He wanted a movie to be as 'un-effectsy' as possible. The shots had to feel real. To this purpose, we did a lot of location work, whereas on the first movie, the majority of the scenes had been captured on stage. The fact that we shot on location, notably in Chicago and Hong Kong, allowed us to ground the movie in reality. We shot as many real elements as possible.

"There is a scene in which Bruce Wayne (Christian Bale) throws a party in his penthouse. Instead of building a set, production decided to use the spectacular lobby of a real office building. It meant that we had to replace everything outside the windows with the scenery that one would expect outside a penthouse. So, we put greenscreens on every window of this lobby and basically used the location as a soundstage, which was quite difficult. But in the end, what we got on screen was this massive space that had a gritty and very realistic feel to it."

Back in Gotham City
Just like on Batman Begins, Gotham City environments and most of the action sequences were assigned to London-based Double Negative. The company ended up creating more than half of the vfx shots, including 170 shots rendered and composited in full IMAX resolution for the special IMAX release of the movie.

In-house Visual Effects Supervisor Paul Franklin led a team that included Senior VFX Producer Matthew Plummer, 2D Supervisor Andy Lockley and co-CG Supervisors Peter Bebb, David Vickery and Philippe Leprince. Rather than have an overall animation supervisor, Franklin opted to work directly with the animation team to develop the stunt and vehicle sequences.

Double Negative used its usual Maya/RenderMan/Shake pipeline, associated with a series of new proprietary tools. "For The Dark Knight, we developed several major new toolsets, the most significant of which was our IMAX rendering and compositing pipeline, which is essentially resolution independent -- the only real limitation was how much server space we could cram into the machine rooms," notes Franklin. "The key components to this new pipeline are a suite of 64-bit compositing tools and a highly optimized 3D asset management strategy linked to a super-efficient lighting and rendering pipe."